Array technology can provide a simple way to explore the expression of a single polymorphic gene or the expression profile of a large number of related or unrelated genes. When the expression of a single gene is examined, arrays are employed to detect the expression of a specific gene or its variants. When an expression profile is examined, arrays provide a platform for examining which genes are tissue specific, carrying out housekeeping functions, parts of a signaling cascade, or specifically related to a particular genetic predisposition, condition, disease, or disorder.
The potential application of gene expression profiling is particularly relevant to improving diagnosis, prognosis, and treatment of disease. For example, both the levels of gene expression and the particular sequences expressed may be examined in tissues from subjects with mental illnesses such as bipolar I disorder, bipolar II disorder, unipolar disorder, schizophrenia, attention deficit hyperactive disorders, obsessive compulsive disorders, anxiety disorders or other related mood disorders, and compared with the levels of gene expression and the particular sequences expressed in normal tissue.
The Diagnostic and Statistical Manual (DSM-IV) published by the American Psychiatric Association serves as the basis for the description, identification and diagnosis of all the mental illnesses covered by this invention. These illnesses include bipolar I disorder, bipolar II disorder, unipolar disorder, attention deficit hyperactive disorder (ADHD) and schizophrenia. At present there are no biological markers to identify these illnesses individually or as a group. Membrane potentials have been used to diagnose bipolar I disorder, bipolar II disorder and ADHD and this technique is described in pending U.S. patent application Ser. No. 10/823,647 and U.S. provisional patent application No. 60/670,237.
The present invention provides for a composition comprising a plurality of cDNA molecules for use in methods of detecting changes in expression of genes encoding proteins that are associated with mental illnesses. Such a composition, and the cDNA molecules, can be employed for the diagnosis, prognosis and/or treatment of mental illnesses that are correlated with differential gene expression. Differential gene expression may also reflect inflammation, proliferation, and/or cell activation which occur secondary to the disease process. The present invention satisfies a need in the art in that it provides a set of differentially expressed genes which may be used entirely or in part to diagnose, to stage, to treat, and/or to monitor the progression or treatment of a subject with mental illnesses, such as bipolar disorder.